1. Field of the Invention
This invention relates broadly to the fields of manufacturing and construction and more particularly to the provision of new general purpose manufacturing and construction elements made from discarded pneumatic tire materials. It also relates to the fields of environmental preservation and waste disposal, more specifically to recycling persistent non-biodegradable materials. Significant contributions are made to all the above fields by providing recycled, useful, and inexpensive materials which are easily made directly from a previously nearly indestructible item of scrap material causing worldwide disposal problems. The primary benefits to the environmental preservation and waste disposal industry are: (1) that recycled products are made from every part of the discarded item thus not creating more waste; (2) that the transformation to very useful products is done with very little energy expenditure; (3) that the entire process is virtually pollution free; and (4) that precious and dwindling forest resources may be preserved because some of the end products produced are contemplated to adequately replace wood in many applications. The very toughness that makes old tire carcasses a difficult disposal problem makes the rubber crumbs produced by this process ideal for an additive to asphalt and paving compositions. The rubber crumbs are also useful as an extender and impact modifier in rigid plastics. It is well known the multitude of plastic products that replace products previously made from environmentally precious wood. Siding for houses is but one example that immediately comes to mind. The artisan will no doubt be able to perceive many other products that may be made with the new raw materials produced in accordance with the principles of this invention. It will become immediately evident that the unique physical properties of the raw material elements produced in the manner herein disclosed will provide important benefits in many areas. The finished article of manufacture may take many forms as will be seen in the remainder of this specification.
As such it will be appreciated that the potential uses are myriad. A comprehensive listing of all the possible fields to which this invention may be applied is limited only by the imagination and is therefore not provided herein. Some of the more obvious applications and end products are mentioned herein in the interest of providing a full and complete disclosure of the unique advantages to be gained by use of this hitherto unknown recycling process.
Highway construction, manufacturing, environmental preservation, and waste disposal are seen as the fields most likely to gain immediate and substantial benefit from this invention. It is to be understood from the outset that the scope of this invention is not limited to these fields or to the specific examples of potential uses presented hereinafter.
2. Description of the Prior Art
The vulcanized rubber pneumatic tire has proved to be both a blessing and a curse to modern society. We can't live without tires and we are Just beginning to realize we can't live with millions of worn out tire carcasses clogging our landfills and littering our environment. Tires are particularly villainous at prematurely filling dump sites because their hollow toroidal shape is particularly volume consuming and they do not easily compress or nest within one another. About the only way anybody ever has disposed of a used tire has been to burn it. This solution has been so unsatisfactory that it is now illegal in most jurisdictions. Burning tires cause a horrible stench and pollute the air with toxic fumes and particles harmful to all life forms. Even expensive modern incineration devices, complete with scrubbers for the exhaust fumes, are inferior for destroying old tires. The steel belting materials clog the incinerator while the particulate carbon and sulfur compounds tend to foul the scrubbers. Additionally, many incineration devices consume electrical energy which serves primarily to transfer the pollution down the river to where the energy is being produced.
The difficulty in discarding worn out tires and the energy and raw materials required to manufacture them has inspired much effort to refurbish them for further use by retreading. These efforts have spawned entire industries.
However, there are several major problems with producing retreads. The new tread which is to be bonded to the old tire must be produced somewhere. Extensive amounts of energy are used to produce the heat required to bond the new tread to the old tire and, even then, that crucial bonding is not always well accomplished. Both the bonding and the production of a new tread surface are, in many respects, just further examples of shipping the pollution down the .river. All told, there is probably as much energy used and pollution produced in the manufacture of a retreaded tire as in the production of the original tire. Here, as in incineration, the steel belts and cords used in modern tires pose severe obstacles to the successful completion of the process. Not all tires can be effectively recycled by the retreading process. For example, if the sidewall or sealing bead is damaged there is no good means to reclaim that tire. The problem here is that a tire must not only have sufficient tread but must also meet stringent standards of flexibility, strength, air permeability, and appearance.
A second alternative of somehow reforming the old tire carcass into other useful articles has been pursued by others with generally limited success. It has been proposed that old tires could be shredded and used as a form of insulation material perhaps mixed with other insulation materials such as vermiculite. This proposal does indeed recognize the important property of extremely low thermal conductivity. The actual shredding process would be extremely difficult especially when steel belts are imbedded in the old tires. Even if the metal were successfully minced up with the rubber it would have to be separated later because it would seriously degrade the thermal insulation properties of the final product. Also, the actual volume of shredded material recovered in this manner would be relatively small with respect to the volume of the original tire carcasses. One would need a mountain of old tires to produce a truckload of shredded rubber insulation material and that truckload might be enough to insulate one house. These relative quantities are, of course, not meant to be precise but merely to point out the fact that there are problems of scale involved with shredding tire carcasses to produce a voluminous product such as household insulation.
Following along with the idea of making some sort of useful product out of the old tire carcasses, there have been numerous proposals to create all kinds of decorative and ornamental articles from the tires. Examples of such uses are flower planters and landscape dividers. Two other applications of limited but useful merit will be familiar to all. Anyone from a farm or rural community will have seen a tire hung from a rope to form the familiar "tire swing". Anyone living on or near a body of water will have seen old tires attached to the sides of docks as bumpers for cushioning the impact of boats. This particular use highlights the important and useful impact absorption properties of the tire material. It has been recorded in the magazine "ABC-American Roofer and Building Improvement Contractor", February, 1978, that old truck tires have been flattened and used as a form of roofing. They are overlapped in an alternating tread-out tread-in pattern to form a watertight seal for this purpose.
Numerous United States Patents have been granted for various and sundry articles made from old tires. The largest group of these Patents are concerned with providing highway safety dividers or barriers thus effectively utilizing the inherent impact energy absorption characteristics of the rubber.
Crude systems for recycling used tire carcasses are old and well known in the art. Many grinders, shredders, mincers, separators, and incinerators have been proposed in the past. All of these systems have suffered from-excessive cost and have tended to create excessive air pollution.
Recently, cryogenic embrittlement techniques have been developed to separate the three main components present in tire carcasses. These components are generally rubber, fiber, and steel. Although these techniques represented a considerable advance over prior techniques, they were very expensive and not economically viable. In accordance with conventional terminology, the term rubber used herein may be taken to mean the chemical compositions developed over the years to form the bulk of standard vehicle tires.
The following known prior art has been directed to providing a cryogenic tire material reclamation technique. As will be seen, the simplicity and effectiveness of my invention is not rivaled in the prior art.
U.S. Pat. No. 4,025,990, issued to Lovette, Jr. on May 31, 1977, shows a tire reclamation system using cryogenic freezing as one of its steps. In most respects the system of Lovette bears little similarity to mine. For example, the instant invention uses airlock entry and exit means to the freezing chamber in order to precisely control the freezing environment. The Lovette device requires a significant amount of energy to run the hammermill, grinding mill, and cyclone screen. In contrast, the components of my system are all operated with relatively low energy requirements. Other significant differences will become apparent as the invention is more fully described.
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.